Man has long known that aeration is necessary to replenish the soil and promote continued growth of plants. Cropland and gardens achieve this aeration by tilling and replanting operations. But in areas such as lawns, golf course greens, athletic fields and cemeteries, these historic methods of aeration are not possible. The detrimental wear and compaction caused by foot traffic and motorized vehicle operation make aeration even more necessary.
Scientists consider 50% mineral matter, 25% air and 25% water, by volume, to be the ideal growth medium for turf grass. The soil should have large pores, called macropores, to ensure air circulation and quick drainage. Equally important are the smaller pores, called micropores, that hold moisture against gravity and make it available for plant roots. The number of macropores and micropores should be approximately equal.
The compression of soil from continuous traffic will destroy the macropores and create micropores thus destroying the balance of the pores with a resulting lack of oxygen and poor drainage which will force root structures to alter their growth pattern. The tight soil resists root penetration and growth causing the root system to grow close to the surface. This shallow root system is more susceptible to environmental damage, poor growth and poor stress recovery in turf grass.
Traditionally, man has tried to combat this type of soil compaction with aerators that drive short spikes on rollers into the soil. This type aeration produces a ripping or tearing effect in the root system as well as creating a compaction layer, called hardpan, below the reach of the spikes.
In order to break through the hardpan without compromising the existing root structure, scientists now recommend aeration penetration of the soil from 8 to 12 inches in depth. Studies have documented increased air flow, drainage and deeper root growth in areas using this deeper penetration aeration method which restores the macropore/micropore balance.
The Deep Drill Aerofier, manufactured by the Flody and McKay Aerofier Co., Inc. of Dunn, North Carolina which is shown and described in U.S. Pat. No. 4,476,938 issued on Oct. 16, 1984 to Leon A. McKay, was designed for this type of aeration. It is a self-propelled unit with a drill head attachment. The drill head has multiple drill bits turning in unison while being lowered into the ground. This allows for deep aerofication penetration of up to ten inches without the accompanying root damage caused by spike aerators as mentioned above. As the drill bits are removed from the ground, loose soil is pulled up and deposited on the surface in an "ant hill" type mound. This mound is scattered over the ground surface and is quickly integrated into the surrounding turf.
To complete the aerofication process, scientists now suggest top-dressing the surface with a sand-based medium. This is currently being accomplished by dumping the top-dressing medium on the soil surface and spreading it to the aerated holes with gardening tools and brooms. This process is extremely time consuming and labor intensive. Since this process involves trying to sweep or push the top-dressing medium across a turf grass surface, there is a bruising effect on the surface grass and a large amount of dressing material is lost in the process.